html {
    box-sizing: border-box;
    background-color: #ffc600;
    font-family: 'helvetica neue';
    font-size: 20px;
    font-weight: 200;
}

body {
    margin: 0;
    padding: 0;
}

*, *::before, *::after {
    box-sizing: inherit;
}

h1 {
    margin-top: 0;
}

.site-wrap {
    max-width: 700px;
    margin: 100px auto;
    background-color: #fff;
    padding: 40px;
    text-align: justify;
    word-wrap: break-word;
}

.align-left {
    float: left;
    margin-right: 20px;
}

.align-right {
    float: right;
    margin-left: 20px;
}

.slide-in {
    opacity: 0; /* 隐去图片，形成空位 */
    transition: all 0.7s;
}

.align-left.slide-in {
    /* 使图片左移，并缩小为原来的 95% */
    transform: translateX(-30%) scale(0.95);
}

.align-right.slide-in {
    /* 使图片右移，并缩小为原来的 95% */
    transform: translateX(30%) scale(0.95);
}

.slide-in.active {
    /* active 时，使图片恢复到原位及原样 */
    opacity: 1;
    transform: translateX(0%) scale(1);
}
